Repeated　wetting　and　drying　is　one　of　the　most　destructive　actions　that　can　induce　continuous　damage　to　in-situ　rocks　in　many　engineering　applications.　The　situation　is　exacerbated　if　the　action　is　coupled　with　flowing　water　conditions.　In　this　work,　the　wet–dry　(W–D)　deterioration　characteristics　of　gypsiferous　rocks　surrounding　underground　excavations　were　investigated.　A　series　of　tests　at　different　W–D　cycles　with　different　flow　rates　(0,　10,　and　20 l/h)　were　conducted　on　gypsiferous　specimens　to　reveal　the　deterioration　behaviors.　The　change　in　rock　pore　structure　was　characterized　by　nuclear　magnetic　resonance　(NMR)　method　and　the　deterioration　characteristics　in　its　mechanical　properties　were　investigated　by　the　P-wave　velocity　test.　Based　on　the　disturbed　state　concept　(DSC),　a　W–D　deterioration　model　was　established.　The　results　showed　that　repeated　W–D　actions　led　to　the　formation　of　visible　cracks　which　enhanced　the　dissolution　of　gypsiferous　rocks,　while　the　loose　particles　detached　from　the　rock　matrix　were　carried　away　by　the　flowing　water,　resulting　in　an　uneven　diameter　reduction　in　the　specimens.　The　damage　of　internal　micro-porestructure　and　enlargement　of　internal　pores　were　induced　also　by　the　combined　action　of　the　W–D　processes　and　water　flow.　The　feasibility　of　using　the　pore　structure　parameters　to　characterize　the　deterioration　in　the　mechanical　properties　of　gypsiferous　rocks　due　to　W–D　actions　at　different　water　flow　rates　was　demonstrated　based　on　the　proposed　deterioration　model.　This　study　can　provide　a　useful　reference　tool　to　help　the　engineering　design　of　tunnels　under　similar　geological　conditions.　©　2022,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Austria,　part　of　Springer　Nature.